Your Digest for Wednesday, Feb 07, 2024 07:59 PM


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[!INFO] Intrinsic muscle nerve supply
All the intrinsic muscles of the hand except the lateral two lumbricals cause supplied by the ulnar nerve.
The lateral lumbricals are supplied by the median nerve.
Brachials plexus is made up of C5 to T1 nerve roots

[!TIP] Mnemonic: Klumpkey the Monkey
monkey hangs -> C8/T1 lesion

Klumpke's paralysis (KP) Erb's palsy
C8 / T1 lesion C5/C6
Claw hand due to unopposed action of long flexors and extensors Shoulder adducted, elbow extended, forearem pronated (waiters tip)
Can have associated Horner's Xn (C8,T1 are in close proximity to sympathetic chain). Also winged scapula
Damage to one can cause damage to the other. more common than Klumpke's
Seen in breech delivery. (upward traction on arm) Shoulder dystocia
Loss of function of lubricals and wrist flexors Deltoid, biceps, brachialis affected.
Lumbricals flex the MCP joints and extend the PIP and DIP joints;
In KP, The wrist and the MCP are extended and the DIP and PIP are flexed.
C8 / T1 - Medial forearm sensory loss sensory loss in lateral forearm, lateral aspect of upper arm.
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Ulnar claw

Medial two lumbrical are supplied by the ulnar nerve;
Lateral two lumbricals are supplied by the median nerve.
In ulnar claw hand, the lesion is similar to klumpke's but limited to the lateral two fingers.


Causes of diabetes insipidus

Central Nephrogenic
Intracranial SOL / pituitary surgery / trauma etc Lithium
Infiltrative diseases: Histiocytosis, Sarcoidosis, (but ?not amy_loidosis) ⬆Ca, ⬇K
Haemochromatosis Demecloclycline
DIDMOAD (ada Wolfram Syndrome) Inherited:
Common- ADH receptor mutation
Rare: aquaporin 2 mutation
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[!INFO] Relevant cerebral lobes
Mnemonic: PITS ->

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Characteristic EDH-epidural/ extradural SDH-subdural
Patient Young, Hx of trauma Old
Aetiology Usually trauma, spontaneous is very rare Commonest is traumatic, cerebral atrophy (old age, chronic alcohol use) is a major risk factor
- Tamponade effect will control rate of bleeding (as it’s venous)
Type of bleed 80% arterial, therefore rapid Mostly venous / small arteries
Site Commonly middle meningeal artery at [[foramen spinosum.png]] Bridging vein or other sites
Plane Potential space between dura and skull Between dura and arachnoid
Presentation Lucid interval → rapid decrease Can be acute or chronic.
Imaging Lens shaped, does not cross suture lines, crosses dural attachments Crescent shaped, crosses suture lines, does not cross dural attachments
- Chronic changes occur: Encapsulation and resorption / hygroma formation
Also seen in trauma most common type seen in trauma
Lower impact, lucid interval present Caused by Higher energy impacts - patient won't regain consciousness
brief, linear contact force to the skull. Can Occur in less severe trauma (antigoagulants, old age are RF)
Arterial or venous. (commonest site = middle meningeal artery);
caused by disruption of vessels secondary to dura separating from skull.
Mechanism: tearing of veins due to relative movement of brain due to acceleration
rare in age > 60 as 'dura is tightly adherent to the skull' highest incidence in 40s to 70s.
most are acute. Can be acute or chronic
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Source

OR
Wernicke = Word Salad. (W - W)

Wernicke's Brocas Conduction aphasia Global aphasia
Receptive Expressive
Fluent Non fluent
"Word salad" "Tip of the tongue" Speech fluent; repetition poor;
comprehension preserved.
All of the above;
can communicate with guestures
Superior temporal gyrus Inferior frontal gyrus Arcuate fasciculus All regions affected
Middle Cerebral artery Middle cerebral artery

[!TIP] Mnemonic: The parietal lobe is responsible for interpretation of "things in space";
Symbols lose meaning - agraphia, acalculia, alexia,
Disorientation
Spatial structure of tactile stimuli is lost - "cortical sensory loss"
Astereognosis

  1. simultagnosis (inability to identify things in context - i.e can see trees but can't recognize Forrest)
  2. Hemispatial neglect

Temporal lobe dysfunction

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[!TIP] Mnemonic:
The temporal lobe seems to be involved in

  1. processing and interpretation of sensory stimuli
  2. predominantly auditory, also visual, smell etc.
  3. Emotional regulation
  4. Memory

Functions:

  1. Processing sensory stimuli - Mainly sound ( but also vision, smell etc)
  2. Memory - Hippocampus. (hippocampus is involved in making long term, emotionally connected memories)
  3. Language comprehension
  4. Understanding social cues
  5. Facial recognition
  6. Emotional regulation -> possibly due to involvement of the amygdala which is located in the medial temporal lobe.
    1. fear is a predominant emotion seen in temporal lobe problems.
  7. Attention
  8. Reward processing and motivation.

Features of temporal lobe dysfunction:

Function Dysfunction
facial recognition prosopagnosia - inability to identify faces
Language comprehension Wernicke aphasia
Processing visual stimuli Visual agnosia
Processing sound Sensoryneural hearing loss, word deafness, difficulty in interpreting sounds
Attention problems paying attention amidst other stimuli <-? difficulty in filtering out sensory stimuli?
Disrupted sensory processing during TLE Temporal lobe epilepsy: not significant motor component as TL isn't involved in motor function.
Features include déjà vu, unprovoked fear, visual distortions, and strange tastes and smells.
Memory Inability to form new long term memories or if severe, loss of previous long term memories associated with self identity ->
which can lead to personality change
Source

Causes of QT prolongation:

Congenital Drugs Other
- Jervell-Lange-Nielsen syndrome (includes deafness and is due to an abnormal potassium channel)
- Romano-Ward syndrome (no deafness)
- amiodarone, sotalol, class 1a antiarrhythmic drugs
- tricyclic antidepressants, fluoxetine
- chloroquine
- terfenadine
- erythromycin
- electrolyte: hypocalcaemia, hypokalaemia, hypomagnesaemia
- acute myocardial infarction
- myocarditis
- hypothermia
- subarachnoid haemorrhage
  1. Amiodarone is the drug of choice for for treatment of haemodynamically unstable VT.
  2. Verapamil should never be used in VT - ?why
    F

The classic description of the left cardiac ventricle is as containing two papillary muscles: the anterolateral and posteromedial.[2] The anterolateral arises from the sternocostal wall, and the posteromedial papillary muscle arises from the diaphragmatic wall of the ventricle. The right ventricle contains three papillary muscles, classically described as anterior, posterior, and septal. Source

Left anterolateral papillary muscles derives from branches of the left coronary artery. The blood supply to the left posteromedial papillary muscles most commonly derives from the right coronary artery Source
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[!INFO] Azithromycin
used as last resort add on therapy
Reduces exacerbation frequency but promotes antibiotic resistance.


Pulmonary arterial hypertension

Pathologic findings in pulmonary arterial hypertension:

Treatment:
Two groups:


Disease modifying drugs in rheumatoid arthritis;
DMARDS are commonly co-prescribed;
Are there any bad combinations?
The drugs are divided into non-biologics and biologics, corticosteroids, and NSAIDS.

Usuallly RA doesn't have adverse effects on pregnancy.
TNF is central in disease pathogenesis.
Order of preference for use of drugs:

Autoimmune diseases in pregnancy

Immune thrombocytopenia in pregnancy

Rheumatoid arthritis in pregnancy

SLE in pregnancy

Viral classification

[!INFO] Key terms:

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Examples:
Hepatitis B - hepadnaviridae
Hepatitis C - flaviviridae
HIV - retroviridae
EBV - herpesviridae
picornaviruses include - enterovirus, coxsackie virus, Hepatitis A
Orthomyxoviridae - influenza virus.
Retroviruses - HTLV-1 and HIV. (HIV uses viral integrase for DNA incorporation)

Antiviral drugs

Source
Antiviral drugs do no "kill" viruses; they only inhibit replication.

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Herpes simplex during pregnancy

[!INFO] Summary
New herpes is bad; worst if onset in T3.
Recurrence of herpes doesn't impose a significant risk.

Acne rosacea

Temp renal physiology

ADH stimulates V2 rectors on principal cells in the collecting duct to promote insertion of aquaporin channels.
The main cells in the collecting duct are principal cells. They

The intercalated cells are responsible for H+ secretion and chloride secretion.

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Metabolic alkalosis

Source
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Chloride responsive Chloride resistant
GI H+ loss HCO3- retention
contraction alkalosis Intracellular H+ shift
Diuretic therapy Hyperaldosteronism
Post hypercapnia Barter syndrome
Cystic fibrosis Gitelman syndrome
Exogenous alkalotic

[!INFO] Pendrin
Is a key transport protein involved in pathogenesis.

"internal potassium balance".

The transcellular shifts in K+ caused by acid base changes.
Basis: In acidosis, about half the H+ is buffered intracellularly. To maintain electroneutrality, intracellular K+ moves outwards into the ECF.

[!INFO] Hypoaldosteronism
In patients with hypoaldosteronism, for example, the mild metabolic acidosis is primarily due to the associated hyperkalemia
UpToDate

Familiar mediterranean fever

Management of ACNE

  1. Comedolytic topics medications - benzoyl peroxide, salicylic acid, and retinoids.
  2. Systemic: isotretinoin and antiandgoren treatment.
    1. Antiandrogens are contraindicated in men.
    2. Isotretinoin reduces sebum production; Vitamin A derivative, contraindicated in pregnancy (even blood donation is contraindicated while on it); congenital malformations can result.
    3. Usually very effective for acne.
  3. Antibiotics supposedly kill the bacteria:
    1. Topical clindamycin
    2. Oral doxycycline

Gynaecomastia

Clinical and pathological correlation

Causes of gynaecomastia

Group Cause Mechanism
Physiologic newborns
Puberty
Old age
Pathologic
Drugs
Cirrhosis or malnutrition
Male hypogonadism - primary or secondary
Tumors
Testicular - germ cell, Leydig cell, Sertoli cell, sex cord
Adrenal - adenoma or carcinoma
Ectopic production of human chorionic gonadotropin
Hyperthyroidism
Chronic kidney disease and dialysis
Rare causes
Enzymatic defects of testosterone production*
Androgen-insensitivity syndromes*
True hermaphroditism*
Aromatase excess syndrome

[!TIP] mnemonic: Drugs causing gynaecomastia
Gay DISCO

  1. Goserelin - Mechanism of Action Goserelin (a gonadotropin-releasing hormone [GnRH] analog) causes an initial increase in luteinizing hormone (LH) and follicle stimulating hormone (FSH), chronic administration of goserelin results in a sustained suppression of pituitary gonadotropins
  2. Digoxin
  3. Isoniazide
  4. Spironolactone
  5. Cimetidine
  6. Oestrogen

Causes of hyperprolactinaemia

#2023GM-NOV/Q30

See also [[Hormone Physiology#Prolactin]]
Pathological causes

Drugs:

Staphylococcal toxic shock syndrome

Homocystinuria

A rare #autosomal-Recessive disorder which presents with

Causes of acute visual loss

Unilateral:

Painful Painless
Corneal abrasion Lens dislocation
Keratitis Vitreous haemorrhage
Acute Glaucoma Acute maculopathy
Hyphema Retinal detachment
Endophthalmitis Retinal artery occlusion
Anterior Uveitis Retinal Vein occlusion
Optic Neuritis Ischemic optic neuropathy

Bilateral

Evaluation of gradual visual loss

[!INFO] Visual loss means loss of one or more of

Pearls


Central Vs. Peripheral vision loss:


Speed of onset

Leading causes of blindness

Retinal vessel occlusion

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Source

Retinal artery occlusion (RAO) Retinal Venous occlusion (RVO)
Less common Much more common
Older population older population
Urgent need of further evaluation Doesn't need further evaluation for cause
Higher risk of ASCVD events
Managed by neurologist - like a stroke Managed by ophthalmologist
Permanent renal death in a few hours.
Commonest causes are emboli:
+ ICA emobli
+ aortic arch, cardiac
Sudden vision loss (curtain coming down) Vision loss ranges from slight to severe
Retinal haemorrhages are common
Vascular causes are the main risk factors Age seems to be the main risk factor
Source

Von hippel-lindau disease

#autosomalDominant
Hallmarks:
retinal and central nervous system (CNS) hemangioblastomas (blood vessel tumors), pheochromocytomas, multiple cysts in the pancreas and kidneys, and an increased risk for malignant transformation of renal cysts into renal cell carcinoma.
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Source

Peutz-Jeghers syndrome

#autosomalDominant

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Gastric polyps mucocutaneous pigmentation

Pituitary adenomas

[!TIP] Summary
Small anterior pituitary tumours (<1cm) are commmon, nonfunctioning and asymptomatic.

Large pituitary tumours (>1cm) are less common and they can cause pressure effects or hormone imbalances.

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In contrast to macroadenomas, pituitary function testing is generally not needed for microadenomas - Medscape

Pituitary microadenoma is usually an incidental finding on MRI head. Patients are asymptomatic unless the tumor is hormonally active.
Pituitary macroadenoma presents with mass effects and potentially hormonal deficiency or hormonal excess. Source

Heart blocks

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[!TIP] Summary:
Mobitz I : OK
Mobitz II : BAD

Alpha-1 antitrypsin deficiency

Management: intravenous alpha1-antitrypsin protein concentrates + smoking cessation, supportive bronchodilators etc .

Source <- Dynamic air trapping in COPD.
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pontine haemorrhage